Welcome John.

Aye, building is half the fun

Power efficiency vs cost has been a trending topic for a long time now.
Dirk has contributed numerous threads in our hardware forum which are interesting to read and a handy reference when looking to build and purchase.
When you decide what you want, I hope you can find it using the affiliate links (top menu).

I'm a long time linux user. It's my weapon of choice.
I'll be interested to hear as you go along about your linux experience, what distro with what equipment etc.
We have a forum for that too. Feel free to kick off a new thread.

Thanks for coming to the forum and introducing yourself.
Its always great to make the acquaintance of a fellow cruncher.